Al-Qaeda on Sunday freed dozens of soldiers captured in battles in southern Yemen, as three suspected militants were killed in an air strike in the north of the country, local and security sources said.

"Al-Qaeda has released 73 soldiers they seized in the south in early March," said a provincial official in the militant stronghold of Jaar.

The soldiers were "driven in two buses from Jaar to Aden," the main southern city, the official said, adding that religious and tribal mediators had secured their release.

On March 4, militants from the Yemen-based Al-Qaeda in the Arabian Peninsula fighting under the banner of the Partisans of Sharia (Islamic law), attacked an army camp near the provincial capital Zinjibar, killing 185 soldiers and capturing scores.

In a statement claiming responsibility for the assault, Al-Qaeda said it was holding 73 soldiers.

The announcement of their release came as rumours circulated the soldiers might be executed.

In the northern province of Al-Jawf, three men where killed in an air raid that targeted their car on Sunday, a security official said.

A tribal source said "the car was completely destroyed and all those inside were killed."

Those in the car were "Al-Qaeda members who were in Al-Jawf to offer condolences to family members of militants killed in the fighting in Abyan," the source said.

The Partisans of Sharia have expanded their control over Yemen's lawless southern and eastern provinces, taking advantage of a weakened central government in Sanaa and months of political upheaval.

The jihadist network intensified its attacks on the security forces after President Abdrabuh Mansur Hadi took office in February pledging to hunt down the militants.

On Tuesday, Hadi held talks with FBI Director Robert Mueller on the growing threat from Al-Qaeda in Yemen, which Washington considers the global network's most active branch.